1. Field of the Invention
The invention relates to a connector comprising a grounding element and a housing of an electrically insulating material, which housing comprises at least one contact element having a contact end, an intermediate part, and a connection end.
2. Description of the Prior Art
Such connectors are known from, e.g., international patent application PCT/IB95/00883 (publication number WO96/13926). This publication concerns a connector for connecting a radio telephone to its base station so as to enable signal and power transmission. Due to the frequent removal and repositioning of the radio telephone on its cradle, there is a need for a reliable connection over the life of the telephone whilst adjusting to the large tolerances in positioning. There is also a need to protect the circuitry of the base station, in particular from electrostatic discharges or ESD that could occur between an external device and the cradle connector or between the contact of the cradle connector when exposed to the environment as is the case when the telephone is removed. PCT/IB95/00883 further acknowledges a continuous demand on provision of more compact and cost effective connection systems and providing a cradle connector that is protected from electrostatic discharge in a cost effective, compact and reliable manner. To achieve the above-mentioned objectives, each of the contact elements is provided with a supple spring means between its connection end and its contact end and two or more contact elements are provided with extensions abutting against a short circuiting bar positioned within the connector.
It is an object of the present invention to provide a further improved connector comprising an electrostatic discharge suppressor.
To this end, the connector according to the present invention comprises an electrically insulating voltage variable medium that is provided between the at least one contact element and the grounding element. The electrically insulating voltage variable medium becomes electrically conducting at a voltage that is substantially higher than the operating voltages of a device for which the connector is intended or of which the connector is part of.
The connector according to the present invention allows, owing to the use of the electrically insulating voltage variable medium is a compact design. Thus, applications of the connector according to the invention is no longer restricted to larger devices, such as the above-mentioned cradles or base station, but can now also be used in smaller devices, such as mobile telephones.
Further, the connector according to the present invention provides electrostatic discharge suppression independent of whether or not the connector is connected to a counterpart or not. This may, for instance, prove especially advantageous in connectors for mobile devices, such as mobile phones or the like.
Electrostatic discharge typically involves a voltage in a range from say 10 to 15 kV. Thus, it is preferred that the voltage variable medium becomes electrically conductive at voltages higher than 1 kV, preferably at voltages higher than 5 kV so as to prevent short circuits from occurring during normal operation and, at the same time, provide effective protection against ESD and similar phenomena.
A very suitable voltage variable medium contains or consists of a polymer. Especially when the polymer is curable or thermosetting, application or inclusion of such a polymer in the connectors according to the present invention can be carried out relatively easily.
The invention is especially advantageous when used in a connector which comprises a plurality of contact elements and wherein the grounding element comprises a shorting or shunting bar that runs along at least some or each of the contact elements. It is preferred that such connectors further comprise a channel that accommodates both the medium and the shorting or shunting bar. Thus, the electrostatic discharge suppression provides simultaneous protection for a plurality or all of the contact elements and can be kept even more compact.
The invention further pertains to a butt-mount connector containing a voltage variable medium as described above. Butt-mount connectors allow compact design and are therefore often used in compact electronic devices. The present invention enables the use of electrostatic discharge suppressors in combination with butt-mount connectors without rendering the latter unsuitable for use in compact electronic devices.